Aftermarket Margins and the Installed Base
Razor/blade engine economics: installed-base scale, services backlog mix and MRO benchmarks, and why aftermarket margins stay hidden in aerospace filings.
Educational analysis for professional use. This guide is not investment advice or a recommendation to buy or sell any security, and it is not personalised.
Profit Follows the Fleet, Not the Delivery Year
Aftermarket economics in commercial aerospace depend on the installed base: engines and airframes in service generate decades of spares, shop visits and long-term service agreement (LTSA) cash flows. New equipment is often sold at a discount; the margin accrues on the tail. Equity screens that stop at delivery counts miss the revenue engine that drives GE, Safran and proprietary parts suppliers.
IATA/Oliver Wyman (Oct 2025) documents engine initial list-price discounts up to 80%+. MRO (maintenance, repair and overhaul) gross margins run 20-35% versus engine OEM manufacturing at −5% to +10%. GE and Rolls-Royce sourced 74% / 66% of commercial engine revenue from MRO in 2024. That mix is why engine backlog skews services-heavy.
GE’s Aftermarket Backlog Already Dwarfs New Equipment
GE is the cleanest filed benchmark for engine installed-base scale:
| Metric | Value | As-of |
|---|---|---|
| Commercial engines installed base | ~45,000 | FY2024 |
| Total backlog | ~$190B | 31 Dec 2025 |
| CES backlog | ~$170B | 31 Dec 2025 |
| CES backlog services share | ~90% | Q4 2024 call |
| Equipment / Services revenue | 29% / 71% | FY2025 |
| CES Equipment / Services | 25% / 75% | FY2025 |
| CES operating margin | 26.6% | FY2025 (blended) |
| FY2025 FCF | $7.7B | FY2025 |
| Book-to-bill (new orders against revenue billed) | ~1.44× | FY2025 (computed) |
Roughly nine-tenths of CES backlog is services-linked. That aligns with the 75% services revenue mix inside CES and the razor/blade model: equipment orders book upfront; services backlog reflects shop visits and LTSA balances rolling forward on the fleet.
GE targets >100% FCF conversion through 2028 (Investor Day). Aftermarket-heavy models convert earnings to cash more reliably than airframe ramps in trough years.
Every LEAP Delivered Adds Another Engine to Safran’s Aftermarket Stream
Safran Propulsion FY2025 mix was OE 35.4% and aftermarket 64.6% of revenue. Propulsion recurring operating margin was 23.0% on the division total; Safran does not file an aftermarket-only margin split.
| Metric | Value |
|---|---|
| LEAP deliveries FY2025 | 1,802 (+28% YoY) |
| FY2026 LEAP delivery plan | ~+15% |
| Adjusted EBITDA | €6.3B |
| FCF | €3.9B |
| Net cash | €1.7B |
LEAP unit backlog is not disclosed in the FY2025 press release; 1,802 deliveries are the throughput proxy. Each LEAP shipped onto an A320neo or 737 MAX adds an engine-year to the aftermarket stream through CFM shop visits and spare parts.
Rolls-Royce Civil underlying operating margin was 20.5% in FY2025, a useful peer comparator. LTSA balance growth at Rolls-Royce illustrates how engine OEMs carry forward service revenue beyond the initial delivery quarter.
Proprietary Parts Skip the Engine Shop-Visit Cycle Altogether
Not all aftermarket economics flow through engine shop visits. Proprietary components and sole-source parts carry some of the highest margins in the set without ever touching an overhaul bay.
TransDigm (FY2025): commercial aftermarket $2.8B (31.8%), commercial OEM $2.1B (23.8%), defence $3.8B (42.6%). Gross profit 60.1%; EBITDA As Defined $4.8B (53.9%). The company explicitly does not use traditional backlog; demand is inferred from purchasing patterns on the installed fleet.
Howmet (FY2025): spares ~21% of revenue; commercial engine spares +44% YoY. Engine Products adjusted EBITDA margin 33.3% (OE + spares blended). Consolidated adjusted EBITDA $2.4B (29.3% margin); FCF $1.4B. Backlog is qualitative only (“record OEM backlog stretching into the next decade”).
Howmet is the bridge case: still OE-heavy on revenue, but spares growth is the installed-base signal.
Why Aftermarket-Only Margins Stay Hidden
Filers report segments that blend OE and aftermarket. Clean aftermarket-only operating margins rarely appear in SEC or Euronext filings.
| Filer | Filed proxy | Limitation |
|---|---|---|
| Boeing | BGS ~18.5% op. margin ex gain | BGS mixes in more than BCA aftermarket alone |
| Airbus | Commercial Aircraft 10.4% EBIT Adjusted | Platforms 89% of external revenue |
| GE | CES 26.6% operating margin | 25% Equipment inside CES |
| Safran | Propulsion 23.0% recurring OM | 35.4% OE revenue inside division |
| Howmet | Engine Products 33.3% Adj. EBITDA | OE + spares blended |
| TransDigm | 53.9% EBITDA As Defined | Mix of commercial, defence, OEM |
We typically apply a ~15-25 pp aftermarket premium over OE on the same chain when inferring steady-state economics from a blended segment. Treat it as a working estimate for the split filers never actually report.
GE Is the Cleanest Aftermarket Teaching Case; Howmet the Messiest
GE Aerospace states its backlog services split outright, rather than leaving it to be inferred from a blended segment margin. The GE Aerospace profile walks through that split.
The Safran profile covers LEAP throughput and what CFM shop visits do to Propulsion’s revenue mix over an engine’s life.
Howmet sits at the other end: no quantified backlog at all, only a qualitative management comment on order strength. The Howmet profile covers what spares growth tells you when a filer won’t put a number on backlog.
For how those segment margins compare across the whole peer set and OE/aftermarket revenue splits, see the OEM vs aftermarket guide. For how aftermarket mix drives multiples, see valuing aerospace.
Count the Fleet Before You Model the Backlog
- Count engines or aircraft in service from filer disclosures (GE ~45,000 commercial engines).
- Map services/backlog share (GE CES ~90% services in backlog).
- Use LTSA and shop-visit commentary where unit backlog is not filed (Safran LEAP).
- For parts suppliers, track spares revenue growth and gross margin instead of aircraft backlog units.
- Apply segment margin proxies with a mix footnote; do not invent aftermarket-only EBIT.
Engine deliveries are the install date. Aftermarket revenue is the annuity. Model the annuity before you capitalise the OEM ramp.
Commercial Aerospace Sector Primer
Delivery rates and the aftermarket annuity are the inputs. This primer takes them to a dual-rate sum-of-the-parts and an EV/EBITDA you can defend.
The Excel model is the primer's two dual-rate sum-of-the-parts builds live across 12 sheets: original equipment capitalised at a cyclical rate, the installed-base aftermarket at a lower annuity rate, summed to enterprise value. Change the delivery rate, the aftermarket dollars per unit or either discount rate and the value per share moves.
Frequently Asked Questions
- What is razor/blade economics in commercial engines?
- Engine OEMs discount new equipment heavily (IATA/Oliver Wyman documents initial list-price discounts up to 80%+) and recover profit over decades via shop visits, spare parts and long-term service agreements on the installed fleet. GE FY2025 CES revenue was 25% Equipment and 75% Services at 26.6% blended operating margin. MRO represented 74% of GE commercial engine revenue and 66% of Rolls-Royce civil revenue in 2024 per IATA.
- How large is GE Aerospace's commercial engine installed base?
- GE Aerospace reported roughly 45,000 commercial engines in the installed base as of FY2024, plus roughly 25,000 military engines. Total backlog was ~$190B at 31 December 2025, with Commercial Engines & Services backlog ~$170B. Management stated ~90% of CES backlog is services (Q4 2024 earnings call).
- Why don't aerospace filers disclose clean aftermarket-only margins?
- Segments blend OE and aftermarket when reported to investors. Boeing's two filed segments, BCA and BGS, blend more into BGS than aftermarket alone. Airbus Commercial Aircraft EBIT Adjusted 10.4% blends Platforms 89% and Services 11%. GE CES 26.6% blends Equipment 25% and Services 75%. Safran Propulsion 23.0% is a division total across OE 35.4% and aftermarket 64.6% revenue. Analysts use the filed segment proxy and footnote the mix.
- How does Howmet fit the installed-base story?
- Howmet sells engine components and structures into both OE production and the spares channel. Spares were ~21% of FY2025 revenue (versus ~17% in FY2024); commercial engine spares grew 44% YoY. Engine Products adjusted EBITDA margin was 33.3% on an OE-plus-spares blended basis. Howmet does not quantify backlog units; management cites record OEM backlog stretching into the next decade (qualitative only).